In recent years there has been substantial interest in millimeter wave semiconductor devices and integrated circuits, and such interest has been enhanced with recent and substantial advances in solid state microwave and millimeter wave diodes which are utilized in a wide variety of power generation, control, and signal processing functions. For example, the frequency-power product of impact ionization avalanche transit time (IMPATT) diodes has been greatly improved in just the past year, and these devices have been successfully operated at frequencies in excess of 140 GHz and at a power output in excess of 120 milliwatts per device. This frequency is about midway in the millimeter wave frequency range, which is generally considered between 30 and 300 GHz, corresponding respectively to wavelengths of 10 mm and 1 mm.
In addition to the rising interest in IMPATT diodes, the well known bulk effect Gunn diode has also received many operational improvements and wide use in recent years, especially in relatively low noise applications in contrast to the higher power applications in which IMPATT diodes have been used.
Some of the millimeter wave applications for these devices include millimeter wave sweep generators, parametric amplifier pumps using stabilized IMPATT oscillators, doppler radar for intrusion alarm systems, aircraft landing systems, and collision aviodance networks, to mention a few.